Oil & Gas Geology ›› 2006, Vol. 27 ›› Issue (2): 209-217.doi: 10.11743/ogg20060211

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Diagenesis of Chang 81 reservoir with low permeability in Xifeng oilfield,Ordos basin

Li Hong, Liu Yiqun, Liu Linyu   

  1. Department of Geology, Northwest University, Xi'an, Shaanxi, 710069
  • Received:2006-01-10 Online:2006-04-25 Published:2012-01-16

Abstract:

The Chang 81 sandstone reservoir in Xifeng oilfield,Ordos basin,is mainly composed of lithic arkose and feldspathic lithic sandstone,and is of typical low porosity and low permeability reservoir with an average porosity of 8.32% and average permeability of 1.33×10-3 μm2.The reservoir has experienced diagenesis,metasomasis,dissolution and cataclasis,and is now in the late diagenetic phase A to B.The mechanical compaction in the early diagenetic phase and the ferruginous carbonate cementation in the late diagenetic phase are the main contributors to the poor poroperm characteristics.According to the characteristics of diagenesis,the braided ri-(ver) delta front sandbody in the study area can be divided into 4 diagenetic facies belts,including compaction and pressolution,weak compaction-carbonate cementation,weak compaction-chlorite-film cementation,and chlorite-film cementation-feldspar corrosion.Sandstones in the latter two facies belts in the core of the main sandbody have good poroperm characteristics and oil-bearing properties,thus they are favorable for hydrocarbon accumulation.

Key words: diagenetic facies, diagenesis, low permeability reservoir, Xifeng oilfield, Ordos basin

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